Amazon has been awarded two patents in which it outlines propellers with robotic adjustable wingtips and legs that act as landing gears to help drones touch down on uneven surfaces.

The e-commerce giant's latest idea describes an "adjustable landing-gear extension" that can be extended or contracted. Amazon says "distance determining elements" would be able to judge how far the drone is from the ground. Sensors on the landing arm would be able to detect contact with the ground and adjust so that the drone is horizontal and not tilted.

This technology could be key if drones deliver fragile packages on tough terrain.

"For example, when a UAV (unmanned aerial vehicle) is landing, the slope of the surface may be determined and the landing gear extensions adjusted based on the slope so that the body of the UAV remains approximately horizontal when the UAV lands and is supported by the landing gear extensions," the filing with the United States Patent and Trademark Office said.

USPTO

The landing gear could also have a "barbed spike" that could screw into the surface for extra stability. Or it could also have a magnet to land on metal surfaces or a "vacuum suction cup."

Amazon said the drone could be made from lightweight materials such as graphite, aluminum or carbon fiber. The top of the drone would have the ability to rotate, allowing the flying machine to correctly position itself in environmental conditions such as wind.

"Specifically, the UAV may be re-oriented while it is landed by rotating the support coupling so that the body of the UAV rotates while the landing gear assembly remains stationary," Amazon's patent said.

In the second patent, Amazon laid out its ideas for robotic propellers that could help the drone face less resistance in the air. The patent outlines adjustable winglets on the propeller, much like those on airplanes. They will help the drone counter the drag created by pressure in the air as it flies.

They will be adjustable and react to environment conditions.

USPTO

"The propellers may be reconfigured at predetermined times during operation of an aerial vehicle, or upon sensing one or more operational characteristics or environmental conditions, as may be desired or required," Amazon said.

The patents were granted on Tuesday after initially being filed in 2015. Tech site GeekWire reported on the patents on Tuesday. Amazon is an aggressive filer of patents and being awarded one does not mean that the idea will necessarily see the light of day.

Still, it highlights how the company is thinking about drone delivery, which it is being tested in the U.K. A recent Amazon patent described a giant flying warehouse that would act as a launchpad for drones, while another one outlined an idea for an unmanned flying vehicle to eject packages that would land in a backyard with the help of a parachute.